Diesel locomotives are the main workhorses in rail freight transport operations. These locomotives typically employ powerful diesel engines such as the well-known EMD line of engines, including EMD 567, EMD 645, and EMD 710 series. During freight operations, parts of a diesel locomotive engine, such as its power assembly, are subject to wear and tear which cause their performance to gradually deteriorate until a point where they no longer provide a satisfactory power output and/or efficiency. It is usually much less costly to rebuild a diesel engine than to purchase a brand new one. Thus, a main function of a railroad machine shop is to dissemble old diesel locomotive engines, to repair, remanufacture, or replace parts of the power assembly, to clean various components of the engines, and then to reassemble the engines into almost new, working conditions. Such an engine rebuilding process is repeated by maintenance engineers on a regular basis.
One important step of reassembling a diesel locomotive engine is to re-install new engine pistons into their respective cylinders. During this step, each piston has to be pushed down in a corresponding engine cylinder and properly seated in the piston carrier. Previously, maintenance engineers would typically re-seat engine pistons with simple specialized tools, such as a T-handle or a “piston and rod holding tool for EMD engines” (Model T51082, sold by Tesco at http://www.tescotools.com/emd-1/pistons-and-valves/t51082-piston-and-rod-holding-tool-for-emd-engines). These hand tools typically include a push rod which has a threaded tip at one end for attachment to the top of a piston and has a T-shaped or ring-shaped handle at the opposite end. An engineer has to hold onto the handle and apply an extraordinary amount of force along the push rod to thrust the attached piston down towards the piston carrier. According to one estimate, it takes about 190-200 pounds of force in order to overcome the friction between the piston ring and the cylinder liner during the piston re-seating process. Since the entire force needed to force the piston down the cylinder has to come from the engineer, he often has to assume a challenging or awkward body position and could suffer from muscle strain. With those simple hand tools, it is also quite difficult to control the alignment of a piston with its carrier.
Sometimes when a piston is extremely tight-fit with respect to a cylinder, engineers had to use a hammer to knock on the handle end of the hand tool. However, the hammering action could cause tremendous impulsive impacts on the piston which may damage the crown of the piston: for example, where the T-handle screws in could crack). It is much more desirable to use a smooth downward movement to re-seat a piston because it also aids in a proper alignment with the piston carrier.
In view of the foregoing, it may be understood that there are significant problems and shortcomings associated with current tools and methods for diesel engine maintenance.